Microsoft Chairman Bill Gates told a crowd in Goleta on March 22 that it may take more than half a century to reduce the world’s carbon emissions by 50 percent as scientists say is needed to prevent severe climate change.

“You’ll never get to absolutely zero, but you have to get to extremely small numbers,” Gate told the fifth annual ECO:nomics Conference. “This is very dramatic … it seems very daunting.”

Gates said he’s looking toward next 10 years for innovation to help solve the problem. He said there should be a policy to encourage experimentation.

Gates said the world needs one of “five miracles,” which include 95 percent carbon capture, which is expensive, and nuclear energy, which is not popular now, even though he’s investing in it.

He said there is a need to build better, fourth-generation nuclear plants. Gates said the world should conduct better “energy farming.” That means getting more power from wind, sun and biofuels, which all require improved storage and transmission.

“We are addicted to super-reliable power,” Gates said. That poses some challenges in the future, he said.

Earlier Thursday, actress and eco-activist Darryl Hannah said the world must change its “stupid or destructive behavior patterns” to avert what she called a “crisis.”

After being arrested three times for protesting what she thought was bad environmental policy, Hannah said she still drives the TransAm she rode in “Kill Bill,” but now the fuel-injection car runs on clean-burning propellant. She admits she gets low mileage from that type of fuel.

As a Sustainable Biodiesel Alliance activist, Hannah advocates use of alternative fuels such as alcohol, biodiesel and waste products, including used vegetable oil.

“Food, energy and fuel should all be produced regionally,” she said. Hannah also advocated living on a smaller scale to use less energy, water and other resources.

As with the BP oil disaster two years ago, Hannah said, “We need too learn from our mistakes.” She told business leaders, “Kids who are your future customers, they get it.”

Hannah recoiled at some comments made at the Goleta conference she said she heard speakers claim Japan’s nuclear disaster last year had no serious effects, while another speaker said more emphasis should be placed on finding how to stretch use of fossil fuels.

Many people will die from the radioactive and toxic effects of the Fukushima nuclear plant meltdown, she said. She said the global climate is in crisis because of the world’s addiction to fossil fuels.

Hannah said the fossil fuel industry has made record profits even in the current economy. “We need to change the paradigm,” she said. “We should make regional biofuels.”

She said she staunchly opposes the proposed Keystone Pipeline, which would move tar sand oil through America’s heartland to Gulf refineries where it would be sold to the highest bidder.

“The public believes it’s our oil,” she said. “It won’t make gas prices go down; Canada’s native communities won’t allow it to go to Vancouver to be refined” because it would cross environmentally sensitive tribal lands.